Effects of post-exercise sodium bicarbonate ingestion on acid-base balance recovery and time-to-exhaustion running performance: a randomised crossover trial in recreational athletes

Abstract

This study investigated the effect of post-exercise sodium bicarbonate (NaHCO3 ) ingestion on acid-base balance recovery and time-to-exhaustion (TTE) running performance. Eleven male runners (stature, 1.80 6 0.05 m; body mass, 74.4 6 6.5 kg; maximal oxygen consumption, 51.7 6 5.4 mL·kg1·min 1 ) participated in this randomised, single-blind, counterbalanced and crossover design study. Maximal running velocity (v-V_ O2max ) was identified from a graded exercise test. During experimental trials, participants repeated 100% v-V_ O2max TTE protocols (TTE1, TTE2) separated by 40 min following the ingestion of either 0.3 g·kg1 body mass NaHCO3 (SB) or 0.03 g·kg1 body mass sodium chloride (PLA) at the start of TTE1 recovery. Acid-base balance (blood pH and bicarbonate, HCO3– ) data were studied at baseline, post-TTE1, after 35 min recovery and post-TTE2. Blood pH and HCO3– concentration were unchanged at 35 min recovery (p > 0.05), but HCO3– concentration was elevated post-TTE2 for SB vs. PLA (+2.6 mmol·L1; p = 0.005; g = 0.99). No significant differences were observed for TTE2 performance (p > 0.05), although a moderate effect size was present for SB vs. PLA (+14.3 s; g = 0.56). Post-exercise NaHCO3 ingestion is not an effective strategy for accelerating the restoration of acid-base balance or improving subsequent TTE performance when limited recovery is available.